Not without edit code.
you can delete in file /components/com_jsn/models/list.php at line 76 this code:

->where('a.block=0')

the line becomes:

$query->select($this->getState('list.select','a.id'))->group('a.id')->from('#__users AS a')->join('left','#__jsn_users as b ON a.id=b.id')->join('left','#__user_usergroup_map as c ON a.id=c.user_id')->where('a.block=0');

Now you can see all user, if you want a list of activated user put in Custom SQL WHERE a.block=0
if you want a list of not approved user put a.block=1
if you want a list of confirmed their email address put a.activation LIKE "___%" (I use this because in some cases the activation not empty)